Velvet transmission

[Dido]

Dear all, my sailboat is equipped with a Ford Lehman 4D254 and a Velvet transmission 10-13-000-003, 2:1 ratio, 1.5 shaft diameter and 19x13 LH 3 blade propeller. When I turn off the engine and start sailing the shaft keep rotating regardless of the position of shifter, forward, reverse or neutral. Is this a sign of defective transmission, if not then are there a device I could install to immobilize the shaft during sailing.

Many thanks for your input.

 

[SoWhat]

Not a problem at typical sailboat speeds. Running on one engine at 10 knots for long periods could result in overheating. The oil pump is not pumping while free wheeling. If engine is not running a PSS seal ay high speeds might need an alterative source of water.

 

[rslifkin]

The Velvet Drive is a hydraulic trans, so once the engine stops turning and the pump on the trans input shaft stops, there's no more hydraulic pressure to engage the clutch packs and the trans ends up in neutral regardless of shifter position.

As long as it's not getting overly warm it's safe to let a Velvet Drive freewheel at typical sailing speeds. And assuming you have a fixed blade prop, it's almost always less drag to let the shaft spin than to lock it in place anyway.

 

[kchace]

Those Velvet Drive transmissions are specd in the manual to be ok to freewheel at sailboat speeds. And yes, it’s completely normal that they do that when the engine is off.

Ken

 

[Taras]

I have velvet drives as well. My question is at what speed would you not feel comfortable letting it free wheel? Sailboat boat of 6 kts is fine, what about 8 kts? I know I'm asking about the grey area here but wanted feedback.

 

[Larry M]

We had a velvet drive on our sailboat. The freewheeling noise was loud. I first went a shaft-lok then to a Max-Prop, a feathering prop. Expensive but worked very well. It also had equal thrust in forward and/or reverse.

 

[kchace]

I think 8 knots would be fine. The manual says this:

“Under sail with the propeller turning or at trolling speeds with one of two engines shut down, the design of the Velvet Drive gear maintains adequate cooling and lubrication.”

Ken